The properties of adenosine triphosphatase from exponential and synchronous cultures of Alcaligenes eutrophus H16

The properties of Alcaligenes eutrophus ATPase (adenosine triphosphatase) were investigated by using subcellular fractions prepared from cells growing in exponential and synchronous cultures. Both the soluble and membrane-bound forms of the ATPase were inhibited non-competitively (Ki 142μm) by Nbf-Cl (4-chloro-7-nitrobenzofurazan), whereas only the membrane-bound enzyme was inhibited (non-competitive; Ki 750μm) by NN′-dicyclohexylcarbodi-imide. Neither the activity of the ATPase nor its sensitivity to these two inhibitors varied during exponential growth. However, marked variations in ATPase activity were observed during synchronous growth, which were characterized by maxima at approx. 0.4 and 0.9 of a cell cycle and minima at approx. 0.1 and 0.6 of a cycle. Sensitivity to Nbf-Cl and NN′-dicyclohexylcarbodi-imide also varied during the cell cycle; maximum inhibition by the former occurred at approx. 0.4 and 0.9 of a cell cycle, whereas maximum inhibition by the latter was located at approx. 0.1 and 0.6 of a cell cycle. Proton conductance by whole cells was also periodic during the cell cycle, the lowest rates occurring at approx. 0.15 and 0.55 of a cycle and the highest rates at approx. 0.4 and 0.9 of a cycle, but →H+/O quotients for the oxidation of endogenous substrates remained relatively constant and indicated the presence of four proton-translocating respiratory segments throughout the cell cycle. These results are discussed in terms of ATPase and respiratory-chain structure and function during the cell cycle of Alcaligenes eutrophus.

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Mitochondrial adenosine triphosphatase of the fission yeast, Schizosaccharomyces pombe 972h−. Changes in activity and oligomycin-sensitivity during the cell cycle of catabolite-repressed and -de-repressed cells

Biochemical Journal ◽

10.1042/bj1620039 ◽

1977 ◽

Vol 162 (1) ◽

pp. 39-46 ◽

Cited By ~ 6

Author(s):

S W Edwards ◽

D Lloyd

Keyword(s):

Cell Cycle ◽

Atpase Activity ◽

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Adenosine Triphosphatase ◽

Total Activity ◽

Stages Of Growth ◽

Synchronous Cultures ◽

A Cell ◽

In Cells

1. Changes in activity of ATPase (adenosine triphosphatase) during the cell cycle of Schizosaccharomyces pombe were analysed in cell-free extracts of cells harvested from different stages of growth of synchronous cultures and also after cell-cycle fractionation. 2. Oligomycin-sensitive ATPase oscillates in both glucose-repressed synchronous cultures and shows four maxima of activity approximately equally spaced through the cell cycle. The amplitude of the oscillations accounts for between 13 and 80% of the total activity at different times in the cell cycle. 3. Oligomycin sensitivity varies over a fourfold range at different stages of the cell cycle. 4. The periodicity of maximum oligomycin sensitivity is one-quarter of a cell cycle. 5. These results were confirmed for the first three-quarters of the cell cycle by cell-cycle fractionation. 6. In cells growing synchronously with glycerol, ATPase activity increases in a stepwise pattern, with two steps per cell cycle; the first of these occurs at 0.54 of the cell cycle and the second at 0.95. 7. These results are discussed in relation to previously obtained data on the development of mitochondrial activities during the cell cycle.

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Chs1p and Chs3p, two proteins involved in chitin synthesis, populate a compartment of the Saccharomyces cerevisiae endocytic pathway.

Molecular Biology of the Cell ◽

10.1091/mbc.7.12.1909 ◽

1996 ◽

Vol 7 (12) ◽

pp. 1909-1919 ◽

Cited By ~ 104

Author(s):

M Ziman ◽

J S Chuang ◽

R W Schekman

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Cycle ◽

Endocytic Pathway ◽

Chitin Synthase ◽

Cell Fractionation ◽

Cell Wall Polysaccharide ◽

Chitin Synthesis ◽

A Cell ◽

Steady State Levels ◽

Membrane Bound

In Saccharomyces cerevisiae, the synthesis of chitin, a cell-wall polysaccharide, is temporally and spatially regulated with respect to the cell cycle and morphogenesis. Using immunological reagents, we found that steady-state levels of Chs1p and Chs3p, two chitin synthase enzymes, did not fluctuate during the cell cycle, indicating that they are not simply regulated by synthesis and degradation. Previous cell fractionation studies demonstrated that chitin synthase I activity (CSI) exists in a plasma membrane form and in intracellular membrane-bound particles called chitosomes. Chitosomes were proposed to act as a reservoir for regulated transport of chitin synthase enzymes to the division septum. We found that Chs1p and Chs3p resided partly in chitosomes and that this distribution was not cell cycle regulated. Pulse-chase cell fractionation experiments showed that chitosome production was blocked in an endocytosis mutant (end4-1), indicating that endocytosis is required for the formation or maintenance of chitosomes. Additionally, Ste2p, internalized by ligand-induced endocytosis, cofractionated with chitosomes, suggesting that these membrane proteins populate the same endosomal compartment. However, in contrast to Ste2p, Chs1p and Chs3p were not rapidly degraded, thus raising the possibility that the temporal and spatial regulation of chitin synthesis is mediated by the mobilization of an endosomal pool of chitin synthase enzymes.

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